There is known a noise reducer for a power converter device including a converter connected to an AC power source, an inverter connected to a direct-current (DC) output side of the converter, and a DC smoothing capacitor connected to a DC intermediate circuit. The noise reducer reduces noise current flowing through the power converter by switching ON and OFF of a semiconductor switching element included in the inverter. The noise reducer includes a noise-current detector for detecting noise current and a noise compensation current supplier that generates noise compensation current for reducing detected noise current and supplies the noise compensation current to the power converter. The noise compensation current supplier includes a series circuit consisting of a transistor, which is an element where output current of the element is controlled by a signal detected by a noise-current detector and with lower withstand voltage than the voltage of a DC intermediate circuit, and a Zener diode (Patent Document 1).